Not rolling stones do gather moss

When we moved in to our current place 2 years ago (in March!); I added a few moderate-sized boulders to the yard—they are a lovely hardscape addition to our more “natural” yard landscape, but I really delight in the moss that grow on them. In fact, when I was at the, um, rock yard, to pick them out, I was particularly focused on the amount of existing (at that time of the year very dry) moss clumps, to the great amusement of the guy driving the tractor to move the rock.